DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports Events Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones AWS Cloud
by AWS Developer Relations
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones
AWS Cloud
by AWS Developer Relations
The Latest "Software Integration: The Intersection of APIs, Microservices, and Cloud-Based Systems" Trend Report
Get the report
  1. DZone
  2. Data Engineering
  3. Data
  4. Partial XMLHttpRequest responses?

Partial XMLHttpRequest responses?

Emil Stenström user avatar by
Emil Stenström
·
Jan. 09, 12 · Interview
Like (0)
Save
Tweet
Share
6.58K Views

Join the DZone community and get the full member experience.

Join For Free

We all know how to make an AJAX request, and fetch some data. But as soon as you need to fetch data incrementally, have the server push data to you, you have to resort to all sorts of complicated stuff. Websockets; with all their different versions and shady support, different kinds of polling, hidden iframes, ActiveX for IE?

The simplest way, that almost workds is partial XMLHttpRequest responses. I first read about them as progressive xmlhttprequests on Kyle Schulz blog, but really think that method should get more recognition.

Note: I’ve only tested this with Webkit, against Twitter’s Streaming API, with a XMLHttpRequest that allows cross-domain requests. I think it works with Firefox too, but it will definitely not work in IE. Sorry.

var xhr = new XMLHttpRequest();
var url = "<streaming-url-on-you-own-domain-or-CORS>";
xhr.open("GET", url, true);
xhr.send();

// Define a method to parse the partial response chunk by chunk
var last_index = 0;
function parse() {
    var curr_index = xhr.responseText.length;
    if (last_index == curr_index) return; // No new data
    var s = xhr.responseText.substring(last_index, curr_index);
    last_index = curr_index;
    console.log(s);
}

// Check for new content every 5 seconds
var interval = setInterval(parse, 5000);

// Abort after 25 seconds
setTimeout(function(){
    clearInterval(interval);
    parse();
    xhr.abort();
}, 25000);

The biggest problem with this method is that the responseText property keeps filling up with data. The longer you receive data, the bigger the data in memory will be. The only way I can see this fixed (today) is to simply kill the connection after a certain amount of data has been received, and open it up again.

I would love to see a better way to do this, from native javascript, without all the numerous hacks that are out there. If you know of a way that fills these requirements, please let me know:

  1. Easy to implement on the client side. Ideally I would like to use XMLHttpRequest, and just get a callback each time the client sends data, with the NEW data specified as a callback parameter.
  2. Easy to implement on the server-side. I can set some headers if you make me, but ideally I would like to use this against existing Streaming APIs (like Twitter’s), without adding custom stuff.
  3. As cross-browser, cross-platform as possible.

Is there a way to get this working? It’s so annoying to see something that’s a curl one-liner, be 100s of lines of code with web technologies…

curl https://stream.twitter.com/1/statuses/filter.json?track=<your-keyword> -u <your-twitter-nick>

Is the web really that far behind?

 

Source: http://friendlybit.com/css/partial-xmlhttprequest-responses/

 

 

Data (computing)

Opinions expressed by DZone contributors are their own.

Popular on DZone

  • When Should We Move to Microservices?
  • What Is API-First?
  • Choosing the Right Framework for Your Project
  • What “The Rings of Power” Taught Me About a Career in Tech

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com
  • +1 (919) 678-0300

Let's be friends: